Ram damping device



March 13, 1962 D. H. ALLBRIGHT 3,024,770

RAM DAMPING DEVICE Filed Sept. 14, 1960 tent iice 3,024,171) .latented Mar. 13, 1952 3,624,770 RAM DAMPING DEJMIE Dennis Howard Ailbright, Coventry, England, assigner to Dunlop Rubber Company Limited, London, Engiand,

a British company Filed Sept. 14, 1960, Ser. No. 56,055 Claims priority, application Great Britain Sept. 29, 1959 3 Claims. ('Cl. 121-33) It is frequently required to slow down or damp the movement of a iluid-pressure operated ram as it ap proaches the end of its stroke and the object of the present invention is to provide a device whereby this may be done.

The invention accordingly provides a fluid-pressure operated ram comprising a ram cylinder containing a ram piston, a damper cylinder, a damper piston in the damper cylinder which is normally ineiective but is movable into a position in which it restricts the ilow of l'luid from the exhaust end of the ram cylinder and means for moving the damper piston from its inoperative to its restricting position when the `ram piston has performed a predetermined portion of its stroke.

Preferably the ram cylinder has a port which is unmasked by the ram piston, towards the end of its stroke, to admit fluid under pressure from the ram cylinder to the damping cylinder and thereby cause the damping piston to move into its restricting position.

One embodiment of the invention will now be described in detail, by Way of example, with reference to the accompanying drawing which is a longitudinal section through the ram and damper cylinders.

The ram includes a conventional ram cylinder 1 containing a ram piston 2, connected to a piston rod 3. The cylinder 1 is provided with an inlet port 4 at one end and an exhaust port 5 at the other end. While these ports are herein termed inlet and exhaust ports, it will be understood that their functions can be reversed, in known manner, to return the ram piston 2 after its oper ative stroke.

Secured alongside the exhaust end of the ram cylinder 1 is a damper cylinder 6 the axis of which is parallel to the axis of the ram cylinder. The damper cylinder 6 is provided at one end with a port 7 communicating with the exhaust port 5 of the ram cylinder `and also with an outlet 8. It has at the other end another and smaller port 9 which communicates with a port 10` in the ram cylinder 1 situated at about one third of its length from the exhaust end. The ports 9, 10 communicate with a space 11 between the end of the damper cylinder and a piston assembly slidable therein. The piston assembly comprises a piston 12 having the usual sealing rings 13 and a plunger 14 of smaller diameter secured to the piston 12. A helical spring 15 encircling the plunger 14 and having one end seating on a step 16 formed in the wall of the damper cylinder, normally forces the piston assembly into the position illustrated and in this position of the assembly the port 7 is unobstructed by the plunger 14.

When iluid under pressure is admitted to the inlet 4, the ram piston 2 is forced to the left. As it nears the end of its stroke, the piston 2 unmasks the port 10, so admitting fluid under pressure to the space 11 and causing the piston 12 to move to the left until it is arrested by a set screw 17, adjustable from outside the damper cylinder 6, which forms an adjustable stop for the adjacent end of the plunger 14. Said end of the plunger is formed with 'a chamfer 18 and the set screw 17 is so adjusted that when the plunger 14 abuts it in an annular gap of predetermined width is provided between the chamfer 18 and a step 19 formed in the cylinder 6, so restricting the ilow of fluid from the port 5 and retarding the movement of the ram piston 2 to an extent determined by the adjustment of the set screw 17.

On the reverse stroke of the ram piston, where no damping is required, the damper piston assembly moves back under the action of its spring 15 to remove the fiow restriction. If damping on the return stroke also is required a similar device may be fitted to the other end of the ram cylinder.

The location along the stroke of the ram piston 2 at which damping becomes effective is determined by the position of the port il@ leading to the damper cylinder. The extent of the damping obtained is varied by adjustment of the set screw 17.

Although the damper cylinder 6 has been illustrated as lying alongside the ram cylinder it is of course obvious that it can be located in any convenient position and connected to the ram cylinder 1 by suitable conduits.

Having now described my invention, what I claim is:

1. A iluid pressure operated assembly comprising a ram cylinder and a damper cylinder, said ram cylinder being provided intermediate its ends with a rst aperture connected to one end of the damper cylinder and being provided at one end with a second aperture connected to the other end of said damper cylinder, a. ram slidable in said ram cylinder under pressure from a source, a damper piston slidable in the damper cylinder when said iirst aperture is uncovered by said ram to connect said damper cylinder with said pressure source, an adjustable stop for said damper piston and restrictor means formed on said damper piston to restrict the iiow of pressure fluid from said second aperture through an exhaust port in said damper cylinder.

2. A fluid-pressure operated ram as claimed in claim l wherein said restrictor means comprises a chamfer on a cylindrical forward extending plunger of the damper piston which abuts said adjustable stop in a position close to an annular step to leave an annular restricting passage therebetween.

3. A ram as claimed in claim 2 comprising a spring disposed in said damping cylinder and urging the damping piston to its inoperative position.

References Cited in the tile of this patent UNITED STATES PATENTS 1,490,633 Peters Apr. 15, 1924 2,674,138 Mize Apr. 6, 1954 2,735,404 Komph Feb. 2l, 1956 FOREIGN PATENTS 393,054 Great Britain June l, 1933 

